Die for shaping sheet metal



(No Model.)

0. W. SWIFT. DIE EOE SHAPING SHEET METAL. No. 383,081. Patented May 15,1888.

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NITED STATES PATENT Orrrcno ORRIN WV. SWIFT, OF NEW HAVEN, CONNECTICUT.

DIE FOR SHAPING SHEET METAL.

SPECIFICATION forming part of Letters Patent No. 388,081, dated May 15,1888.

Application filed August 29, 1887. Serial No. 248,106. (No model.)

To all whom it may concern.-

.t tlBe it known that I, ORRIN W. SWIFT, of New Haven, in the county ofNew Haven and State of Connecticut, have invented a new Improvement inDies for Shaping Sheet-Metal Articles; and I do hereby declare thefollow ing, when taken in connection with accompanying drawings and theletters of reference marked thereon, to be a full, clear, and exactdescription of the same, and which said drawings constitute part of thisspecification and represent, in-

Figure 1, a vertical section through the die and punch separated; Fig.2, a transverse section through a carriage-lamp reflector; Fig. 3, aface view of a carriage-lamp reflector; Fig. 4, a vertical sectionthrough the punch and die in the closed position.

This invention relates to an improvement in dies for shaping articlesfrom sheet metal, such as are to a certain extent cup'shaped, and inwhich it is desirable to make the face of an ornamental or irregularcharacter, the invention being specially adapted to the formation ofreflectors for carriage-lamps. These reflectors are usually drawn up indies, the faces of the two dies being of a shape corresponding to theouter and innersurfaces of the reflector. In so striking up thereflector the contact of the face with the metal portion of the diedefaces it to such an extent that subsequent polishing is necessary, andit is impracticable undcr such method of manufacture to produce thereflectors from metal which has been previously burnished.

The object of my invention is to avoid contact of the face-surface ofthe sheet metal with the metal of the die, whereby I am enabled toproduce the reflectors from sheet metal previously burnished, and sothat com ing from the dies the same burnished surface is retained andwithout defect; and the invention consists in construction of the dies,as hereinafter described, and particularly recited in the claim.

A represents the lower or stationary die, which may be fixed upon theanvil of a press in the usual manner. In this die is a recess, 13, theoutline of which corresponds to the outer edge of the article to beproduced-=say square, as is the usual shape for a carriage lampreflector. The bottom of this recess may be flat or of any desirableshape, but the depth of the recess must be greater than the depth of thearticle.

Above the die A the punch or follower C is arranged. The diameter ofthis punch is less than that of the cavity 13 below by the thickness ofthe metal to be struck.

The under face of the punch C corresponds in shape to the inner surfaceof the reflector.

In Fig. 2 I illustrate a transverse section of the reflector, and inFig. 3 a front view of the same. The surface of the reflector usuallypresents a concave center with a bead surrounding it, and the surfaceoutside the bead being of a convex shape, as shown, the edge of thereflector being turned back from the front, as at a, with usually aflange, 1), around the edge.

The blank of sheet metal from which the reflector is to be produced,having a finely polished and burnished surface, is laid upon the die Aover the cavity 13, the burnished side downward, and, as indicated inFig. 1, cl representing the blank. Then the follower is forced downwardupon the blank, carrying it into thedie, as indicated in Fig. 4. Themetal of the blank as it is pressed into the die forms a complete closepacking between the follower and die, so that the air in the die cannotescape. This confined air becomes a cushion in the die to resist thedescent of the blank and punch. The compression of this air forces thesheet metal to perfectly conform to the shape of the face of the punch,and thereby causes the under or burnished surface of the blank to assumethe same shape, and this without bringing the face of the metal intocontact with the surface of the cavity. The compressed air alone actingupon the surface cannot deface that surface. Therefore when the punch iswithdrawn and the formed reflector removed its face-surface retains thefinelyburnished character which it originally possessed and anysubsequent operation of finishing is avoided. Again, whereas in strikingthe metal between a punch and die of cor responding faces more or lesswrinkling of the metal will be produced, by employing the cushion ofcompressed air as the resisting-sun face upon which the metal is shapedall wrinkling is avoided, the drawing of the metal being perfectlyregular and uniform. This illustration of dies for shaping a reflectorwill be sufficient to enable those skilled in the art to shape otherarticles. One essential point to be specially noticed is that the cavityin the die must be deeper than the article, so that when the punch andthe blank are forced into the recess there will be a space in the recessbelow the face of the article Where the air is compressed as a cushionupon which to shape the metal.

I claim- The herein-described improvement in dies for shaping sheetmetal, consisting of a die having a cavity in outline corresponding tothe outline of the article to be produced, but ofa depth greater thansuch article, combined with a follower or punch, having its under faceshaped corresponding to the shape of the reverse or innerside of saidarticle, the said punch adapted to close a cavity of the die and forcethe sheet metal placed between it and the said cavity into said cavityand upon the ORRIN W. SWIFT.

Witnesses:

FRED C. EARLE, J. H. SHUMWAY.

